Stabilization of CsPbBr Nanowires Through SU-8 Encapsulation for the Fabrication of Bilayer Microswimmers with Magnetic and Fluorescence Properties.

All-inorganic cesium lead halide (CsPbX, X = Cl, Br, I) perovskite nanocrystals have drawn great interest because of their excellent photophysical properties and potential applications. However, their poor stability in water greatly limited their use in applications that require stable structures. In this work, a facile approach to stabilize CsPbBr nanowires is developed by using SU-8 as a protection medium; thereby creating stable CsPbBr/SU-8 microstructures. Through photolithography and layer-by-layer deposition, CsPbBr/SU-8 is used to fabricate bilayer achiral microswimmers (BAMs), which consist of a top CsPbBr/SU-8 layer and a bottom FeO magnetic layer. Compared to pure CsPbBr nanowires, the CsPbBr/SU-8 shows long-term structural and fluorescence stability in water against ultrasonication treatment. Due to the magnetic layer, the motion of the microswimmers can be controlled precisely under a rotating magnetic field, allowing them to swim at low Reynolds number and tumble or roll on surfaces. Furthermore, CsPbBr/SU-8 can be used to fabricate various types of planar microstructures with high throughput, high consistency, and fluorescence properties. This work provides a method for the stabilization of CsPbBr and demonstrates the potential to mass fabricate planar microstructures with various shapes, which can be used in different applications such as microrobotics.